Foam parts for vehicle seats are known in practice, said foam parts serving for padding the seat structure and being intended to provide the user of the vehicle seat with the highest possible level of seating comfort. Generally, the seat padding comprises a foam part for the seat cushion and a foam part separate therefrom for the seat backrest. Each of the two foam parts has a central region and two side cheeks. In a foam part for the seat cushion, the central region of the foam part supports the buttocks and the rear of the thighs of the occupant of the vehicle seat on the underside, whilst the two seat cheeks laterally bear against one respective thigh and, as a result, are able to absorb transverse forces on the occupant, in particular during cornering. In a foam part for the backrest, the central region of the foam part supports the back of the occupant at the rear, whilst the two side cheeks laterally bear against the back and, as a result, are able to absorb transverse forces on the occupant.
A foam part, in particular for a vehicle seat, comprising a first foam layer facing a user and a second foam layer remote from the user is disclosed in DE 202 02 042 U1, wherein the first foam layer has a hardness and/or density which is different relative to the second foam layer. The foam part has a plurality of holes in the central seat surface.
DE 20 2007 002 196 U1 discloses a foam part, in particular for a vehicle seat, having a first foam layer facing a user and a second foam layer remote from the user and an intermediate layer arranged between the foam layers. The foam part has a system of holes for improving the properties of conveying moisture.
EP 1 068 094 B1 discloses a foam part comprising, in order to increase the level of comfort, a plurality of comfort tubes which are integrally formed on a base body of the foam part and which are adjacent to one another, said comfort tubes extending upwardly away from the base body, substantially perpendicular to the seat surface, and being denoted as tubular portions. When the occupant sits down, initially the comfort tubes are compressed, whilst the base body is only slightly deformed. The base body is further compressed only after considerable deformation of the comfort tubes. As a result, a two-stage seating characteristic with increasing cushion hardness is achieved. The comfort tubes have holes extending fully through the foam part.
A foam part comprising a plurality of blind holes is disclosed in U.S. Pat. No. 5,816,661 A, said blind holes extending from a substantially planar foam partial surface into the foam part in a direction substantially perpendicular relative to the foam part surface.
Two-zone foams are known from the prior art, wherein by using different foam materials the central region is configured to be softer than the side cheeks. As a result, firstly the seating comfort is intended to be enhanced and secondly the side support for the user is intended to be improved. To this end, cut foam layers are often used in the central region and hard foam inserts are often used in the side cheeks. To prevent the user from falling down through the lap belt in the event of a crash, frequently an anti-submarining function is provided by an additional component made of a particle foam material, for example EEP (expanded polypropylene). The aforementioned additional components increase the costs and reduce the durability of the foam parts. Additionally, thin foam thicknesses are only possible to a limited extent.
A foam part is disclosed in WO 01/74557 A1, comprising a first region made of foam having a first composition and a second region made of foam having a second composition, wherein between the first and the second region a network of polyethylene, jute, gauze, non-woven fabric or the like is arranged. This foam part, however, does not fulfill the highest comfort requirements when the occupant sits down, in particular not when a very soft cushion layer is initially desired when the occupant sits down. A comparable cushion structure is also disclosed in WO 2010/102785 A2.
A combination of tubular portions as disclosed in EP 1 068 094 B1 and a horizontal separating plane between a first region of the foam part having a first composition and a second region of the foam part having a second composition as disclosed in WO 01/74557 A1 was not regarded hitherto as being able to be produced.